Tuckey and Dehaven: Fish assemblages found in tidal creek and seagrass habitats in the Suwannee River estuary 



103 



tats with those collected in tidal-creek habitats in 

 the Suwannee River estuary. We performed com- 

 parisons of monthly collections offish found along 

 tidal-creek shorelines and those found in seagrass 

 habitats to define fish assemblages and incor- 

 porated abiotic parameters as potential factors 

 influencing the assemblages. We also compared 

 length distributions of species in each habitat to 

 examine the success of YOY recruitment and the 

 subsequent influence of YOY recruitment on fish 

 assemblages in order to understand the nursery 

 function of each habitat. 



Methods 



Study location 



This study took place in the Suwannee River estu- 

 ary, which lies along the gulf coast of Florida, 

 extending from just north of the Suwannee River 

 to Cedar Key (Fig. 1). The Suwannee River emp- 

 ties directly into the Gulf of Mexico forming an 

 unusual open estuary that stretches 13 kilometers 

 north of the river mouth, southeastward to the 

 islands of Cedar Key, and extends approximately 

 8 kilometers offshore (Leadon'). The Suwannee 

 River estuary is shallow (water depth <2.2 m below 

 mean sea level), and has semidiurnal tides with 

 a tidal range of 0.7 m. The shoreline is relatively 

 undeveloped; the city of Cedar Key (pop. 898) along 

 the southeastern edge of the estuary and the small 

 town of Suwannee approximately 4.8 kilometers 

 inland along the Suwannee River are the only 

 populated areas. The remainder of the coastline, 

 consisting of the Lower Suwannee and Cedar Keys 

 National Wildlife Refuges and the Cedar Key State 

 Preserve, is owned by the public. 



Study design 



Randomly selected sites were sampled monthly within 

 tidal-creek and seagrass habitats from January 1997 

 through December 1999. Juvenile and small adult fish 

 from each site were collected using a 21.3-mxl.8-m 

 nylon seine with 3.2-mm mesh and a center bag measur- 

 ing 1.8-mx 1.8-mx 1.8-m. Sampling methods depended 

 on the habitat sampled, and all seines were deployed 

 during daylight hours. 



Collections in tidal creeks consisted of six hauls per 

 month in 1997 and increased to nine hauls per month 

 in 1998 and 1999. Tidal creeks consisted of soft mud, 

 deep channels, oyster bars, and steep banks. Shoreline 

 vegetation included saltmarsh cord grass {Spartina al- 



Leadon, C. J. 1979. Unpubl. manuscr. Environmental 

 effects of river flows and levels in the Suwannee River sub- 

 basin below Wilcox and the Suwannee River estuary, Florida, 

 59 p. Suwannee River Water Management District Interim 

 Report, 922.5 County Road 49, Live Oak, FL 32060. 



Figure 1 



udy area showing location of tidal-creek and seagrass seine hauls in 

 e Suwannee River estuary, located on the gulf coast of Florida. 



terniflora) and needle rush (Juncus roemerianus) near 

 the creek mouths and changed to a variety of freshwa- 

 ter marsh grasses and terrestrial vegetation upstream. 

 The seine was set from a boat in a semicircular pattern 

 along the shoreline, retrieved onshore, and sampled an 

 average area of 68 m- per haul. Shoreline areas inun- 

 dated with vegetation were not sampled if the water 

 depth was greater than 0.5 m in order to reduce the 

 interference of vegetation during sample collections. 

 Sampling in tidal-creeks was limited to the shoreline 

 because the water was too deep in the channels to 

 deploy the seine. In addition, despite the importance 

 of oyster bar habitat, oyster bars located inside tidal 

 creeks were not sampled because they interfered with 

 the proper deployment of the seine. 



Seagrass habitats generally surrounded the major is- 

 lands near Cedar Key, including North Key and nearby 

 islands (Fig. 1). In addition, vegetated patches extended 

 from North Key northwestward to the mouth of the Su- 

 wannee River and were present in shallow areas ap- 

 proximately three kilometers west of the Suwannee River 

 (Fig. 1). Dominant seagrass species in the Suwannee 

 River estuary included turtle grass (Thalassia testudi- 



